Kaplan Nursing Entrance Practice Exam

How do enzymes affect chemical reactions occurring in substrates?

1. They slow down the reaction

2. They change the reaction products

3. They speed up chemical reactions

4. They convert substrates into energy

The correct answer is: They speed up chemical reactions

Enzymes play a crucial role in facilitating chemical reactions within biological systems, primarily by acting as biological catalysts. They significantly speed up reactions by lowering the activation energy required for a reaction to occur. This means that reactions can proceed much more quickly than they would in the absence of the enzyme. Enzymes work specifically on substrates, which are the reactants that bind to the enzyme's active site. By binding to these substrates, enzymes stabilize the transition state, making it easier for the reaction to proceed. This process enhances the overall rate at which products are formed without the enzyme itself being consumed in the reaction. The other aspects associated with enzymes, such as altering the reaction products or converting substrates into energy, do not accurately describe their primary function. Enzymes do not fundamentally change the products of a reaction, nor do they create energy; rather, they facilitate the reactions that lead to energy release or transformation. Hence, the correct answer regarding the effect of enzymes on chemical reactions occurring in substrates is that they speed up chemical reactions.